This invention relates generally to power tools and more specific to a power abrading tool having particular application for polishing and grinding.
Power abrading tools of the type to which the present invention generally relates are used, for example, in sheet metal repair work for automobiles, grinding the surface of metal dies and surface polishing or grinding of other materials. Typically, these tools are hand held. In the past, abrading tools of this type have rotated an abrading pad mounted on the tool in one direction about an axis to polish or grind a surface contacted by the abrading pad. However, it has been found that continuous rotation of the abrading pad leaves marks on the surface being abraded. In order to achieve the best results, the abrading pad is rotated at high speed, causing substantial vibration of the tool. Vibrations of this type present the risk that an operator who uses the tool frequently and for long periods of time could develop pseudo-Raynaud's disease (a vibration syndrome occurring, for example, in users of chain saws and other equipment tending to vibrate in operation).
Japanese patent disclosure Hei 7-55162 discloses an abrading tool which converts rotational motion of its motor into reciprocating motion of the abrading pad to improve the quality of the polishing or grinding done by the tool. Reciprocating motion is achieved by linkage including a master gear and multiple gear racks. Thus, all of the force supplied by the motor is transmitted to the abrading pad through the intermeshing of gears. As a result, the teeth of the gears and gear racks are subjected to large loads, and experience wear and fatigue. Therefore, the tool has a relatively short operating life before repair or replacement will be required. In addition, high-precision machining of the gear tooth surfaces are required if the gear teeth are to mesh correctly, which makes the tools complicated and expensive.
In the normal operation of an abrading tool, substantial quantities of particulates from the surface along with fine abrasive dust from the abrasive material on the abrading pad are generated and become airborne. The particulates and dust gets into the eyes of the operator and can also be inhaled. Thus, use of the abrading tool can create an unhealthy work environment.